Microwave Engineering August/September 1999 Cover story In this issue we take a look at some key areas for the future of the wireless communications industry with a paper on getting the best out of the DECT cordless system and techniques to provide more efficiency with multi-carrier power amplifiers. Millennium or millstone? Against a backdrop of increasing penetration rates for terrestrial mobile communications, the reported lack of customer interest in satellite mobile systems may be something of a surprise. Should it be? The amount of customer data available so far is pretty limited, so we should bear in mind that limitation when analysing any figures that have already appeared, but the Iridium Low Earth Orbit (LEO) satellite system doesn't appear to have got it's hardware into every high street alongside the bubble-wrapped pre-paid terrestrial mobiles. It is an impressive feat to have successfully launched dozens of satellites and developed hand-held hardware that can communicate with them from anywhere in the world, and represents a major-infrastructure investment for the next millennium. Alas, the applause handed out to major infra-structure projects has often not been accompanied by hard cash for the first investors. The railways in the 19th century, the channel tunnel in the late 20th century and others have gone through pain for the initial investors on their way to, hopefully, gain in the long term. Satellite TV services have witnessed the same kind of transition with a period of financial pain proceeding the commercial success. The satellite TV example also includes further similarities to the satellite mobile systems. By the time the services were ready to go live, the noise figure for the microwave transistors at the front end of the home satellite receivers had improved to such an extent that cheaper low power satellites became viable vehicles for the transmission of the signals direct to homes, avoiding the need for more expensive satellite platforms. In mobile communications, the GSM system has developed so rapidly and been deployed in many major countries so there is no need for a large, expensive satellite phone when a business executive travels from Europe to China or India. With the joint factors of technology having moved on, and the historical record of a tough business climate when major infra-structure projects get off the ground, the difficulties faced by Iridium should not be a surprise. Companies like Motorola, Qualcomm and Loral took brave decisions when they invested in the new satellite mobile systems and they deserve to see a decent return on that investment, but it could take a while! Paul Jackson

Contents In focus Casting the net for broadband wireless; Models under debate at device workshop; New On-Line data service. Internal and external view of latest version of Radiant Network's intelligent node for broadband wireless access Focus on Broadband & satellite communications Standards and trials on target for 3G; Extra dimension for UMTS cells; Satellites home in on multimedia. Integrated EM simulation and circuit synthesis in PC-based CAD Eagleware claims that GENESYS 7 is the company's most significant platform release in 6 years. Todd Cutler gives some specific examples of em simulation and circuit synthesis using the new code. 1999 European Microwave Week Preview The European Microwave Week has rapidly become Europe's most important premier exhibition and conference week for our industry. Peter Russer and Larissa Vietzorreck from the TU München give their personal view on the highlights of the week. Hans Hartnagel and Bernhard Walke add their insight into GAAS'99 and European Wireless'99. RF architecture for the near future evolution of DECT In this paper, M Burgos-García, J. Gismero-Menoyo, A. Fernández-Durán, J. Llamazares-Alberola, B. Notario-Pérez, G. Núñez-León and A. Asensio-López present some results of the ESPRIT project TWIST (Twin Carrier Single Transceiver BS for PCS). The main focus is the performance requirements of the next generation DECT-based services and the optimisation of the RF architectures necessary to support them. A 5-6 GHz switch using low cost plastic packaged PIN diodes Short range wireless LANs are being developed for use in the ISM frequency bands between 5.15 and 5.875GHz. Using low cost, plastic packaged, surface mount components, such as PIN diodes, is problematic because of package parasitics. In traditional designs, using packages like the SOT-23, coverage is limited to about 2.5GHz. Gerald Hiller and Peter Shveshkeyev of Alpha Industries describe here, a new design for an SPDT switch in the 5-6GHz range using PIN diodes in a low inductance SOT-23 package. The design has performance approaching 1dB insertion loss and 20dB isolation. Achieving high-efficiency in multi-carrier base-station power amplifiers The trade off between power amplifier efficiency and linearity is well known. Peter Kenington of WSI describes a precorrelation technique with a feed forward system which promises to provide improved efficiency. Sommaire d' articles Zusammenfassung der Artikel New Products and Data European Microwave Week Product Preview Calendar Classified Catalogue Update & Appointments